Weather Briefing at 20/10/2020
On the 20th of October 2020 convective activity is observed over the northern fringes of southern Africa (SAF), mainly at the moist sector of the Angola Low pressure system (Fig. 1). There is also a cloud band extending from SE Angola towards NE South Africa, however, regions of high reflectivity as shown in the satellite image, are mainly comprised of altocumulus clouds. Deep convection over this extended cloud band is only observed over Eswatini. For this reason, it would be safest to claim that the extended cloud band of Fig. 1 does not display a Tropical Temperate Trough event, however this is a claim based on just visual inspection.
SAF is located between two semi-permanent subtropical high pressure systems, the South Atlantic High pressure system (or "Saint Helena High") and the South Indian Ocean High pressure system (or "Mascarene High") (Fig. 2). Both systems are major drivers of moisture transport towards the mainland region (Fig. 3) and exert a severe influence on weather conditions over SAF (Xulu et al., 2020).
Figure 1: Infra+ imagery with pseudo-colours for cloud top temperatures <-33oC, indicative of deep convection at 20/10/2020.
Figure 2: Surface pressure (in shades and contours) at 20/10/2020.
Figure 3: Surface wind (shaded) and surface pressure (contours) at 20/10/2020.
*All maps are taken from Windy